1. Field of the Invention
The present invention relates to a wavelength service providing apparatus in wavelength multiplexing transmission, more specifically, to a wavelength service providing apparatus in an all-optical network constructed by all-optical nodes that include no OEO (optical-electrical converting) part.
2. Description of the Related Art
Conventional optical networks are constructed by connecting optical nodes including optical cross connects (OXC) by transmitting devices such as WDM devices (hereinafter, referred to as WDM devices) and transmission lines (hereinafter, referred to as WDM lines). In the WDM device, an OEO part and a wavelength multiplexing and demultiplexing optical filter which wavelength-multiplexes or wavelength-demultiplexes an optical signal are included. To an optical node, a transponder including an OEO part is connected, and services for a user are provided via this transponder.
It has been proposed that an all-optical network is constructed by eliminating conversion into electrical signals by deleting the OEO part from the WDM device. According to the all-optical network, the network can be constructed at low cost, and signal delays in the network can be reduced.
In the all-optical network, wavelengths are limited in wavelength path setting, however, the factor to limit the band is only the wavelength multiplexing and demultiplexing optical filter, so that the band is not limited as long as the wavelength multiplexing and demultiplexing optical filter has a characteristic (bandwidth) to transmit a requested band (bit rate) without deterioration. Therefore, a user can freely request a band at the time of wavelength path setting request.
Patent Document 1 proposes an optical network in which means for autonomously advertising and collecting available wavelengths in a transmission line is provided in an optical network transmission device (node) and route computation of a wavelength path is performed based on the available wavelengths collected by the means.
[Patent Document 1] Japanese Published Unexamined Patent Application No. 2004-297230
When a service is provided to a user via a transponder, the band of the wavelength path is limited by the band of this transponder. To make it possible for a user to freely request a band, many transponders must be prepared according to the bands requested by the user, and this is not realistic. Under a condition that the number of transponders to be prepared is limited, wavelength service flexible provision is difficult.
In the optical network proposed in Patent Document 1, computation of a wavelength path is performed based on available wavelengths at each node, and this prevents a path setting failure that is caused by wavelength limitation. However, this does not include a wavelength variable function and a band variable function for a user, so that flexible wavelength service provision is difficult.